To escape or not to escape an ampersand Options

[pandy]

It's my understanding that ampersands (in the text) don't have be escaped in HTML but should be escaped in XHTML. Now a situation arose when someone wrote "Q&A" in her HTML document. The verdict is the same from both validators: "Error: unknown entity A".

I understand what's happening, but I'd like to know if this is a glitch with the validators or if it says somewhere that an ampersand can't occur unescaped in a string unless it's followed by a space.

[pandy]

Hmm, in the HTML 4.01 spec it actually says:
"Authors should use "&" (ASCII decimal 38) instead of "&" to avoid confusion with the beginning of a character reference (entity reference open delimiter). Authors should also use "&" in attribute values since character references are allowed within CDATA attribute values."
http://www.w3.org/TR/html401/charset.html#h-5.3.2

So was I wrong? Should ampersands be escaped in HTML too? Always or only in the situation I describe above?

[Darin McGrew]

I couldn't find where it was documented, but the basic rule (in HTML) is that the ampersand needs to be escaped unless what follows is a character that is not allowed in character entity names. That's why an ampersand followed by a space doesn't need to be escaped: a space cannot be part of a character entity name. But I try to escape them all. You never know when someone will come along and change "A T & T" to "AT&T"...

IIRC, XHTML is more strict, but I don't recall its rules.

[pandy]

I couldn't find where it was documented, but the basic rule (in HTML) is that the ampersand needs to be escaped unless what follows is a character that is not allowed in character entity names. That's why an ampersand followed by a space doesn't need to be escaped: a space cannot be part of a character entity name. But I try to escape them all. You never know when someone will come along and change "A T & T" to "AT&T"...

Thanks. If you happen to remember where it's documented, please let me know.

IIRC, XHTML is more strict, but I don't recall its rules.

Totally strict.
http://www.w3.org/TR/xhtml1/#C_12

[pandy]

but the basic rule (in HTML) is that the ampersand needs to be escaped unless what follows is a character that is not allowed in character entity names.

Yeah, Å&Ä&Ö validates.